Randall Fuller | The Book That Changed America: How Darwin’s Theory of Evolution Ignited a Nation | Viking | January 2017 | 25 minutes (6,840 words) 

The excerpt below is adapted from The Book That Changed America, by Randall Fuller, which explores the impact of Darwin’s Origin of Species on American intellectual life. This story is recommended by Longreads contributing editor Dana Snitzky

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“How many a man has dated a new era in his life from the reading of a book!”

-Henry David Thoreau, Walden

Detail from the single illustration that appeared in the first edition of the Origin of Species. Via Wikimedia.


537 plants!

With the possible exception of Asa Gray, no American read the Origin of Species with as much care and insight as Henry David Thoreau. Throughout the first week of February, he copied extracts from the Origin. Those notes, which until recently had never been published, comprise six notebook pages in a nearly illegible scrawl. They tell the story of someone who must have read with hushed attention, someone attuned to every nuance and involution in the book. In their attention to detail, they suggest someone who assiduously followed the gradual unfolding of Darwin’s ideas, the unspooling of his argument, as though the book of science were an adventure tale or a travel narrative.

He was drawn to Darwin’s compendium of facts, which illustrated the delicate interplay of causes leading to the survival or extinction of species. Darwin wrote, “The number of humble-bees in any district depends in a great degree on the number of field-mice, which destroy their combs and nests.” Thoreau copied the sentence into his notebook, probably because he enjoyed the cause-and-effect relationship it implied. He had always been interested in the quirky, arcane detail. “Winged seeds are never found in fruits which do not open,” he read in the Origin, transcribing the sentence into his natural history book. He recorded the strange (if incorrect) statement that “cats with blue eyes are invariably deaf,” something Darwin had gleaned from a work on zoological anomalies by Isidore Geoffroy St. Hilaire, who mistakenly assumed that all blue-eyed cats were deaf rather than the majority, as is actually the case.

He also admired Darwin’s genius for experimentation. Thoreau had described his own efforts in Walden to disprove the local myth that the pond was of unusual depth. With a stone tied to the end of a cod line, he “could tell accurately when the stone left the bottom, by having to pull so much harder before the water got underneath to help me”— a procedure that enabled him to chart the pond’s topography and discover its shallows and depths. He had even provided a map for interested readers. Now he discovered a similar impulse in Darwin. The British naturalist wanted to determine how far birds might transport seeds caught in their muddy feet; this would explain how identical plant species might be found thousands of miles apart. From the silty bottom of a pond near his home he procured some “three table-spoonfuls of mud,” which “when dry weighed only 6¾ ounces.” He kept the mud in his study for six months, “pulling up and counting each plant as it grew; the plants were of many kinds, and were altogether 537 in number; and yet the viscid mud was all contained in a breakfast cup!” The charm of the experiment resided in its simple ingenuity; from common household items Darwin had made a marvelous discovery: 537 plants!

Thoreau was most urgently drawn to Darwin’s ideas. That the struggle among species was an engine of creation struck him with particular force. It undermined transcendentalist assumptions about the essential goodness of nature, but it also corroborated many of Thoreau’s own observations. While living on Walden Pond, he had tried to discover the “unbroken harmony” of the environment, the “celestial dews” and “depth and purity” of the ponds. “Lying between the earth and heavens,” he wrote, Walden “partakes of the color of both.” But sometimes a darker reality intruded upon this picture. “From a hilltop you can see a fish leap in almost any part; for not a pickerel or shiner picks an insect from this smooth lake but it manifestly disturbs the equilibrium of the whole lake.” Something portentous and uneasy lurks about this sentence. The “simple fact” that animals must consume other animals to survive upsets Thoreau; it disturbs the equilibrium of one who wishes to find harmony and beauty in his surroundings. Thoreau tries to laugh it off, calling the dimpled lake the result of “piscine murder.” Yet Darwin provided an explanation for nature’s murderous subtext. Competition and struggle influenced “the whole economy of nature.” It drove species to change and adapt. It created. It was the cost of doing nature’s business.

* * *

Why do precisely these objects which we
behold make a world?

By the time he finished the first chapters of Darwin’s book, Thoreau had seized upon two of its principal ideas. The first was variation: the essential building block of natural selection. Variation received more attention than any other topic in the Origin, mainly because it provided the “means of modification” that enabled organisms to adapt. In the past Thoreau had considered variation from a transcendentalist’s perspective. “I expected a fauna more infinite and various,” he noted with disappointment one spring day, “birds of more dazzling colors and more celestial song. How many springs shall I continue to see the common sucker (catostomus Bostoniensis) floating dead on our river! Will not Nature select her types from a new fount?” Written five years before Darwin’s book was published, the passage reveals a basic tenet of transcendentalist philosophy: Thoreau expects Nature to answer to the demands of his imagination, to serve human needs. But the dead fish he finds each spring in the Musketaquid River also suggested to him an imperfect fit between species and environment.

Following this line of thought now, he copied a number of passages about variation and hereditability, noting for instance the puzzling phenomenon of young horses born with stripes on their shoulders. Why did those stripes disappear as they aged? “How simply is the fact explained,” wrote Darwin, “if we believe that these species have descended from a striped progenitor, in the same manner as the several domestic breeds of pigeon have descended from the blue and barred rock-pigeon!” (Darwin’s point was that the history of a species was encoded in the body, that physical characteristics provided clues about relationships to ancient progenitors.) Thoreau also copied another remark under the heading “Variability of flowers,” which stated that species belonging to the same genus tended to share characteristics, such as variations in color, while those belonging to separate genera did not.

What really interested him, however, was Darwin’s discussion of geographical distribution—the same topic that had engaged Asa Gray a decade earlier. In 1850 Thoreau had noticed a pine seedling in his yard, miles from any other pine, prompting him to wonder how it had gotten there. He began to study the way squirrels transported nuts and seeds from one location to another; then he followed the aerial voyages of milkweed spores and dandelion seeds. Soon he was observing cockleburs and other barbed seeds that attached themselves to animals and clothing, and for a while he considered whether the railroad might play a role in dispersing nonnative seeds to new locations. The question he was trying to answer was one he had asked in Walden: “Why do precisely these objects which we behold make a world?” Thoreau wanted to understand how the oak and pine woods surrounding Concord had sprung into existence. Why did this locale support robins and butternuts rather than, say, parakeets and pecan trees? How had each living thing come to inhabit its particular spot on the planet?

By concerning himself with this topic, he was at the forefront of natural science. Alfred Russel Wallace, whose wide-ranging travels had given him keener insight into the distribution of living things than almost anyone else in the world, would eventually explain the significance of the problem in his book Island Life (1880): “We can never arrive at any trustworthy conclusions as to how the present state of the organic world was brought about until we have ascertained with some accuracy the general laws of the distribution of living things over the earth’s surface.” In his own travels on the Beagle, Darwin had discovered that physical barriers—oceans, deserts, and mountains— often confined plants and animals to highly circumscribed regions. The Galápagos Islands were but one example. Sometimes an identical species was scattered across distant continents, even across vast oceans—as in the case of the Japanese flora found in eastern North America. While Louis Agassiz claimed that such examples implied separate and divine creation, a consensus was beginning to emerge within the scientific community that species were migratory and dynamic, settling wherever climate and resources facilitated their growth.

Darwin was convinced that the distribution of plants and animals shed light on evolutionary development, especially when a species became isolated and developed on its own. Some of the most delightful passages in the Origin of Species describe the experiments he conducted to determine how organisms scattered across the globe. He immersed seeds in saltwater for months at a time, then planted them to see if they would grow. He calculated the distance these seeds might travel across the ocean while immersed. (He determined that some could travel as much as 924 miles by prevailing Atlantic currents.) As for animals, he placed duck feet in a tank of water containing minuscule freshwater snails to see if the tiny creatures would take hold of the webbing. Revisiting his old travel notes, he discovered that a water beetle blown onto the deck of the Beagle had traveled some forty-five miles; this led him to speculate how insects and birds might cover enormous distances during a gale.

These experiments not only revealed how the world might have become populated; they also suggested just how accidental was that process. Far from the carefully organized scheme Agassiz and other special creationists described, Darwin’s world was the product of random and haphazard occurrences. The seeds of plants blew wherever the wind took them and germinated wherever there was enough sun and moisture. Animals followed land bridges or were swept away by flash floods or hurricanes; they were isolated on tiny islands in the middle of the ocean. Nothing was predetermined, nothing organized by design. General laws might govern these actions, but at the individual level, chance prevailed.

A contemporary portrait of Thoreau. (AP Photo)

Because he was already interested in the topic, Thoreau transcribed more passages from Darwin’s chapter on geographical distribution than from any other in the Origin. He carefully noted Darwin’s assertion that “I have not found a single instance, free from doubt, of a terrestrial mammal (excluding domesticated animals kept by the natives) inhabiting an island situated 300 miles from a continent or great continental island—.” And he meticulously followed Darwin’s argument that isolated islands might produce special evolutionary conditions. “[The French naturalist] Bory St. Vincent long ago remarked that Batrachians (frogs, toads, newts) have never been found on any of the many islands with which the great oceans are studded,” Darwin wrote. “I have taken pains to verify this assertion, and I have found it strictly true. I have, however, been assured that a frog exists on the mountains of the great island of New Zealand.”

Thoreau wrote down this passage and appended a remark that showed just how thoroughly he had absorbed the intricacies of Darwin’s discussion: The frog, he asserted, was surely “spawned not there.”

* * *

Every one has heard that when an American forest is cut down a very different vegetation springs up.

Ultimately it was Darwin’s method that left the deepest impression on Thoreau. The book was infused with a point of view: humorous and humane, stubbornly rigorous, breathtaking in its originality. As Thoreau pored over the Origin, he encountered many of his own thoughts packaged and reformulated in a style that was not just scientific but something we would now call Darwinian. In Walden, Thoreau had described a natural world prodigious in death: “I love to see that Nature is so rife with life that myriads can be afforded to be sacrificed and suffered to prey on one another; that tender organizations can be so serenely squashed out of existence like pulp,— tadpoles, which herons gobble up, and tortoises and toads run over in the road; and that sometime it has rained flesh and blood!” Thoreau was again trying to place nature’s profligate waste within a larger philosophical context. Describing the stench of a dead horse “in the hollow by the path to my house,” he claimed that the fetid atmosphere of decomposition indicated “the strong appetite and inviolable health of Nature.”

Darwin’s theory was grounded on similar observations. Nature might be responsible for countless “exquisite adaptations” and “beautiful diversity,” as he put it, but beneath those adaptations and diversity was an incessant struggle. “Every one has heard that when an American forest is cut down,” he wrote, “a very different vegetation springs up. . . . What a struggle between the several kinds of trees must have gone on during long centuries, each annually scattering its seeds by the thousand; what war between insect and insect—between insects, snails, and other animals with birds and beasts of prey—all striving to increase, and all feeding on each other or on the trees or their seeds and seedlings, or on the plants which first clothed the ground and thus checked the growth of the trees.”

This picture of strife and competition is similar to Thoreau’s version of a natural world, “so rife with life that myriads can be afforded to be sacrificed and suffered to prey on one another.” But while Thoreau thought nature’s monumental destruction was necessary for its health, Darwin was less certain. “Throw up a handful of feathers, and all must fall to the ground according to definite laws,” Darwin exclaimed, “but how simple is this problem compared to the action and reaction of innumerable plants and animals which have determined, in the course of centuries, the proportional numbers and kinds of trees now growing on . . . old Indian ruins!” Nature was neither fable nor allegory; it was, rather, a handful of feathers falling as randomly as gravity allowed.

* * *

The term spreadsheet was not in use then; it is possible Thoreau invented a prototype.

Darwin’s portrait of a teeming, pulsating natural world deeply resonated with Thoreau. The Origin of Species revealed nature as process, as continual becoming. It directed one’s attention away from fixed concepts and hierarchies, toward movement instead. It valued moments of evanescent change above all others. If it endowed each organism with a history, it also pointed to a future that was impossible to predict.

For Thoreau, this aspect of the Origin seemed to finish a sentence he had long been struggling to articulate. Once uttered, that sentence seemed to snap the natural world into place. Reading the Origin, Thoreau discovered someone else who understood nature as he did: abounding and vibrant, each niche swarming, each interstice filled with life, each living thing a small part of constant change, a participant in struggle and development, brimming with potential and significance.

Throughout the late winter and early spring of 1860, he continued his daily walks, his diligent measuring and collecting. He spent the cold New England evenings hunched over his journal. But now his prose kindled with a new energy. And something else happened. For eight years Thoreau had patiently compiled mountains of phenological data— information about the timing of nature’s seasonal events. Over the years he had noted the flowering dates of hundreds of plants and recorded what environmental scientists now refer to as “leaf-out” and “ ice-out” dates: that brief period when trees first show their leaves and when the ice on ponds melts.

Immediately after finishing Darwin’s book, Thoreau began the tedious task of extracting and collecting this information. He reread his journals— thousands of pages— and copied the relevant information onto random slips of paper. A receipt from the family pencil-making business, for instance, became the repository of phenological information from 1852. Snow levels from 1854, which Thoreau recorded with a notched walking stick, were written on another scrap. As he carefully combed through his journals, he placed an X by each entry he transcribed.

Sketch of clouds and rain from Thoureau’s journals.

When he was finished with this monumental task, he found he had copied information about more than one hundred trees and some sixty shrubs. He had described the height of grasses, the size of red maple leaves in May, the dates during which the “leaves of goldenrod [were] obvious.” He recorded the growth of fir trees, of larches, the leafing-out of the fever bush, waxwork, red cedar, tupelo, red currant, poison sumac. He noted the day in which “chicadees have winter ways.” He entered the date on which he first noticed the scent of decay.

With this process complete, he gathered his slips of paper and transcribed the information once again. This time his data went into a series of spreadsheets. (The term spreadsheet was not in use then; it is possible Thoreau invented a prototype.) These sheets of paper were nearly the size of a newspaper. On each one Thoreau listed a month, with a column devoted to every year from 1852 to 1860. Into these columns, in tiny, nearly illegible handwriting, he recorded all the information he had gathered.

What was he up to? The simple answer is that we don’t entirely know. He may have been doing what scientists invariably do when their aggregated data become too large and unwieldy: organizing them into sets. But the painstaking work he began in 1860 enabled Thoreau to capture and quantify the processes of growth and death in nature— to discover patterns in nature’s chaotic creativity. It also allowed him to determine if Darwin’s theories held true in the natural environs he knew so well. In Walden he had precipitously leaped into wishful hypothesizing, drawing from a bank of thawing mud all sorts of conclusions about the human and the divine. The spreadsheets presented something radically different: a natural world sharply restricted to facts. If Thoreau hoped to find some law or principle that might unify nature, he now believed he first had to build a solid foundation of evidence.

Around this same time, he began incorporating ideas he derived from reading Darwin into a new lecture he was writing for the Concord Lyceum. That work was entitled “Wild Apples,” and it is arguably the first piece of literature on either side of the Atlantic to be inspired by the theory of natural selection.

* * *

A natural world that resembled a democracy more than a kingdom.

Bronson Alcott failed to recognize the Darwinian references sprinkled throughout Thoreau’s latest lecture. He thought “Wild Apples” “a celebration of the principles of Nature, exemplified with much learning and original observation: beginning with the Apple in Eden and down to the wildings in Concord.” Alcott sat in the Town Hall and “listened with uninterrupted interest and delight” while Thoreau punned on Adam and Eve, on crab apples, on Johnny Appleseed. The lecture was a perfect example of Thoreau’s ability to spin literary gold from the simplest materials.

By focusing on wild apples, Thoreau was making his standard argument for the uncultivated and untamable aspects of life. He traced the history of apple cultivation, sprinkling his talk with a decade’s worth of facts and observations he culled from his notebooks and journals. Concord residents must have delighted to hear the village eccentric expound on the apple’s place in Greek mythology and Homeric epic, to learn of the numerous binomial Latin names for apple varieties used by science, to hear pungent descriptions of the taste of different apples, including the acrid crabapple. They must have recognized with delight the “old farmer” Thoreau quoted as saying that apples in November “‘have a kind of bowarrow tang.’”

What they most likely did not notice was the influence of Darwin, which courses like a subterranean stream through the loamy prose of Thoreau’s lecture. He traced the geographical distribution of apple trees “throughout Western Asia, China, & Japan.” He described how animals helped disperse apple seeds, and he portrayed the fruit tree as an example of artificial selection, having been transmuted from an indigenous shrub to “the most civilized of all trees” by careful breeding over many generations. Referring to Darwin’s discussion of dog breeders, he asked, “Who knows but like the dog, [the apple] will at length be no longer traceable to its wild original (No tree is more perfectly domesticated). It migrates.”

By the time he delivered his lecture on “Wild Apples” in late February, Thoreau had long since finished reading Darwin’s groundbreaking book. He continued to dwell on it, however, focusing especially on the book’s third chapter, “The Struggle for Existence.” Darwin’s portrait of the “war between insects, snails, and other animals with birds and beasts of prey” captured a dynamic he had observed on his countless walks into the woods. But he was becoming more interested in the way this war also linked creatures together—something Darwin described as the way “plants and animals most remote in the scale of nature, are bound together by a web of complex relations.” In Darwin’s vision of nature, species and individuals honed themselves in strife. They came into being through continual friction with one another. “Many cases are on record showing how complex and unexpected are the checks and relations between organic beings,” Darwin wrote, “which have to struggle together in the same country.” Thoreau didn’t express it in quite the same way, but he seems to have begun envisioning a natural world that resembled a democracy more than a kingdom, its citizens connected and yet perennially jostling for advantage. As winter came to a close, this fascination increasingly expressed itself in Thoreau’s research into trees.

Sketch of a tree from Thoreau’s jouranls.

One of Darwin’s examples stood out in particular— a passage in the Origin describing a Staffordshire estate. The land, which probably belonged to Darwin’s father, was a large, barren heath. A generation earlier several hundred acres had been fenced off and planted with Scotch fir, the only pine variety native to Europe. Twenty years later the difference between the two areas was astonishing—“more than is generally seen in passing from one quite different soil to another,” Darwin wrote. Twelve plants that did not exist on the heath flourished among the pines. Six insectivorous bird species, also wholly absent on the heath, lived there— implying a significant alteration in the insect population, as well. “Here we see how potent has been the effect of the introduction of a single tree, nothing whatever else having been done, with the exception that the land had been enclosed, so that cattle could not enter.”

It was a simple but brilliant insight. By amassing details about plants and animals, Darwin had grasped how new environments might come into being. He could not trace every step that had created this new ecosystem—he had not observed it for the twenty years it took to develop—but he had a plausible theory to explain why the transformation had occurred. By introducing a new species to an established environment, humans had completely thrown off-kilter the dynamics of competition and coexistence, creating opportunities and disasters in its wake. An alteration in nature’s equilibrium had introduced a chain of advantages and disadvantages to countless species, radically transforming the landscape.

Thoreau latched onto this particular moment in the Origin for several reasons. For one, it implied that the history of an environment was recoverable. If one accepted the premise that perpetual struggle between species led to the creation of place, then one could uncover its history and thereby determine why “precisely these objects which we behold make a world,” as he had written in Walden. The passage in the Origin also reinforced the idea that such histories were provisional and unpredictable. Each living thing contained the potential for countless actions and reactions, and these in turn contained innumerable paths of development that were impossible to manage. Nature was alive, in other words, not static. And one other aspect of Darwin’s story about the Staffordshire estate intrigued Thoreau: its human element. A completely new landscape had sprung into existence when a sentient being decided to introduce pine trees. This simple act had helped create a complicated environment, a new fact in the world. Thoreau had long suspected that people were an intrinsic part of nature— neither separate nor entirely alienated from it. Darwin enabled him to see how people and the environment worked together to fashion the world. Put another way, the Origin provided a scientific foundation for Thoreau’s belief that humans and nature were part of the same continuum.

Which isn’t to say he adopted the book unequivocally. That spring he continued to grapple with its unrelenting empiricism and with the inductive method of science more broadly. “Science in many departments of natural history does not pretend to go beyond the shell,” he observed a few days before visiting a forest fire in Acton, “i.e., it does not get to animated nature at all.” For Thoreau, merely measuring and describing nature failed to capture its essence. Take the dog, for example. What was most interesting about the animal was “his attachment to his master, his intelligence, courage, and the like, and not his anatomical structure or even many habits which affect us less.” Other aspects of the dog— its relationship to its kind, its fondness for warmth and touch, its interactions with people—conveyed core attributes far better than physical descriptions. Science missed the bigger picture. It failed to grasp what the ancient Romans would have called the animus of nature: its spirit, its mind, its purpose.

At times, Thoreau’s thought bordered on the nostalgic. He longed for the transcendentalist’s confidence in a natural world infused with spirit. He considered his increasing scientism an unwelcome sign of aging, as if the sap and vigor of youth were slowly petrifying. But he continued collecting data, continued filling his journal with notations on the arrival of the robin and bobolink, the budding of the spiraea and the Missouri currant.

* * *

His most widely read piece of writing during his lifetime.

“Henry Thoreau’s discourse before the Middlesex [County] Agricultural Society” was a resounding success, Bronson Alcott wrote in his journal in late September. The society’s fair was held annually in Concord, drawing enormous throngs of people from neighboring towns and villages. Because this was high-minded New England, the event combined self-improvement with agricultural contests and exhibits. Alcott and Emerson had both delivered lectures in the recent past, their inspirational messages punctuated by the plaintive lowing of penned cattle and sheep. Cash prizes ranging from three to ten dollars were awarded for “best porkers,” “best geese,” and “best stallion.” There were countless other honors for finest apples, best-made boots, sweetest peaches and plums, best watermelon, butter, bread, and flowers. John Brown’s daughter, Sarah, received a dollar award for her exquisite needlework.

Darwin. (Via: Wikimedia Commons)

That year the fair took place “under rather unfavorable auspices,” because of “the very inclement state of the weather.” The skies were purple with storm clouds, and a silvery rain slanted off and on, dousing the fairgrounds. In an effort to stay dry, people crowded into the exhibition hall, which was “ornamented by suspending carpeting from the upper part of the building.” By two o’clock the weather had cleared enough to allow the marching band to escort a crowd down Main Street and into the Town Hall, where Thoreau delivered what became his most widely read piece of writing during his lifetime. “The Succession of Forest Trees” was soon reprinted in newspapers across the country, first by his acquaintance Horace Greeley at the New-York Tribune, and then by many other smaller periodicals. The essay was the result of Thoreau’s encounter with Darwin.

Despite its evolutionary overtones, Alcott enjoyed his friend’s talk “on Nature’s Methods of planting forest trees by animals and winds,” finding it “admirable and interesting” and every bit as entertaining as “Wild Apples.” The lecture proposed to explain why oak forests were replaced by pine forests when cut down and vice versa— a phenomenon Emerson, Horace Greeley, and many other reasonably informed observers considered an impenetrable mystery. Darwin had observed in the Origin of Species, “Everyone has heard that when an American forest is cut down, a very different vegetation springs up.” One theory held that the appearance of new forests was the product of spontaneous generation (the scientific term at the time was abiogenesis): plants and animals simply came into being, wondrously if inexplicably, animated by some mysterious spark that was either chemical or divine. This idea accorded well with the idealistic science of Agassiz, and in 1859 one of his assistants, Henry James Clark, announced that he had observed microscopic animals come into existence from decomposing muscle. At a meeting of the American Academy, “Professor Agassiz corroborated Mr. Clark’s statements most fully, and spoke of the discovery as one of the very greatest interest and importance.”

Thoreau considered this nonsense. Spontaneous generation was a form of magical thinking. People wanted to believe that plants and animals sprang miraculously into existence; they harbored an innate need to find mystery and the supernatural within everyday life. That sort of thinking was unjustified, however, because it ignored the causal relationships that occurred in nature. Since the mid-1850s, Thoreau had filled his journals with observations about the mechanisms that enabled seeds to disperse. He had carefully observed and described burrs, pollen, and maple wings, hypothesizing how each might travel before germinating. As town surveyor, he had measured dozens of woodlots, paying special attention to the saplings struggling to survive in the deeply shadowed undergrowth. He was confident that plants did not spring from nothing.

* * *

I have great faith in a seed.

Thoreau was close to Darwin’s position. He assumed the universe was governed by laws, but he also believed that the products of those laws occurred in a more or less random way. He hovered between design and chance, between idealism and materialism. Which is why his argument in “The Succession of Forest Trees” is so remarkable—for Thoreau locates mystery and wonder within materialism.

His touchstone is the seed: an emblem of renewal and vitality. Standing before the audience at the Agricultural Fair, Thoreau announced that he had found some “long extinct plants” growing in the ruins of a cellar. “Though I do not believe that a plant will spring up where no seed has been,” he said, “I have great faith in a seed.” Here he was dispelling the myth of spontaneous creation, but he was also arguing on behalf of a new kind of magic, a new source of awe. “Convince me that you have a seed there, and I am prepared to expect wonders. I shall even believe that the millennium is at hand, and the reign of justice is about to commence, when the Patent Office, or Government, begins to distribute, and the people to plant the seeds of these things.” His point was that nature’s fecund banks of seeds bear witness to a world of wondrous scope and intricacy. Millions upon millions of seeds and spores are produced and scattered, broadcast by the air and by animals in order that a few plants may find their niche and grow. The countless complex interactions necessary to produce a single maple may be the result of nothing intelligent, omniscient, or all-seeing. But something almost as wondrous replaces this intelligence: a natural world that is blindly self-directing, a world that is driven by struggle and contingency, a universe authored not by some abstract Almighty—but by itself. The world, Thoreau suggests, is its own autobiography.

Darwin's_finches_by_Gould (1)
Darwin’s finches. Via Wikimedia.

“The Succession of Forest Trees” reflects a conflict between two visions. One brims with divinity, the other is purely mechanistic. One carries with it a rich heritage of religious belief, the other whispers that God is redundant amid the promise of new discoveries and more complete knowledge. Thoreau moves fluidly between the two, shuttling between the divine and the here-and-now, between theism and materialism. And he endows each with the other. In the address’s final paragraph, he describes seeds as “perfect alchemists I keep who can transmute substances without end.” The word transmute is important here: it alludes to Darwin’s transmutation theory as well as to the potent magic of alchemy, the ancient art of transforming base metals into gold. Thoreau had recently planted some squash in his garden. “Here you can dig,” he informed his audience, “not gold, but the value which gold merely represents; and there is no Signor Blitz about it.”

He was speaking of Antonio Blitz, a popular magician of the era famous for his ventriloquism, plate spinning, and his so-called “egg bag,” a linen sack from which he produced dozens of eggs out of thin air. In this offhand reference to the Welsh-born magician, Thoreau sums up the ambiguities of Darwin’s theories in its first year of publication, capturing both the uncertainties and the longings they created. He argues that another form of mystery and magic is still available, one divested of an intervening providence but nevertheless producing wonder at the deep, irreducible materialism of nature.

As such, “The Succession of Forest Trees” is an early response to a world Darwin had introduced— a place divested of God and yet made wonderful by science, a world of weakened faith and exciting discovery. (Emily Dickinson suggested some of the pain of living in this new reality when she wrote, “Nature is a haunted house”; though God once inhabited the natural world, He has since vacated the premises.) Comparing the wonders of seeds and the cheap magic of Blitz, Thoreau concluded with satire: “Yet farmers’ sons will stare by the hour to see a juggler draw ribbons from his throat, though he tells them it is all deception. Surely, men love darkness rather than light.”

We all believe in magic, Thoreau suggests. We all need to feel that there is something more. But the danger is that this need obscures truth. The world is filled with magic, Thoreau asserts, is rich with mystery—just not the kind that religious tradition has led people to expect and rely upon. In order to experience these things, one has to relinquish certainty, to abandon old faiths and old patterns of belief. One has to live in the nick of time, between orthodoxy and the unknown, searching for knowledge and insight amid perpetual irresolution.

* * *

Constant new creation.

With Darwinian natural selection in mind, Thoreau wrote, “The development theory implies a greater vital force in nature, because it is more flexible and accommodating, and equivalent to a sort of constant new creation.”

Constant new creation. The phrase represents an epoch in American thought. For one thing, it no longer relies upon divinity to explain the natural world. Only a decade earlier Thoreau believed he had found evidence of a divine “Artist” working in the unexpected medium of thawing mud. He had been encouraged to think this way by Emerson, who claimed that every physical fact was the outward representation of a spiritual truth. Emerson had prodded Thoreau to look through nature—not at it—in order to perceive the godhead. To a degree, Thoreau had always resisted this approach; he loved the hard surface of things too much. But now, within the short span of a year, Darwin had propelled him toward a radically different vision of creation that could be explained without an Artist. “The development theory” suggested a natural world sufficient unto itself—without the facade of heaven. There was no force or intelligence behind Nature, directing its course in a determined and purposeful manner. Nature just was.

Darwin_Tree_1837 (1)
Charles Darwin’s first sketch of an evolutionary tree (1837), with the famous appearance of “I think.” Via Wikimedia.

Thoreau would continue to develop these ideas into the next year, when the concept of secession—not succession—preoccupied most of the nation. “It is a vulgar prejudice that some plants are ‘spontaneously generated,’” he wrote in March 1861, one month before the start of the Civil War, “but science knows that they come from seeds, i.e. are the result of causes still in operation, however slow and unobserved.” If divine intervention was unnecessary to produce plants, then the world was governed by luck and coincidence to a degree most people refused to acknowledge: “Thus we should say that oak forests are produced by a kind of accident.”

* * *

One world at a time.

We will never know how far Thoreau might have absorbed and extended Darwin’s theory. Nor can we know what insights he might have extracted from applying the principles of variation and natural selection to his beloved woods and fields. An accident of another sort befell him during the final month of 1860. “I took a severe cold about the 3d of December,” he noted in his journal, “which at length resulted in a kind of bronchitis, so that I have been confined to the house ever since.”

Most likely he contracted influenza from Alcott—it was a particularly bad winter for the illness, and he had visited when the philosopher was still contagious. Thoreau managed to deliver a lecture in Waterbury on December 15, his voice ragged and wheezy as he spoke. Then he remained in bed until nearly Christmas, impatient to return outside and continue his investigations. While he lay in bed, South Carolina declared that “the union now subsisting between South Carolina and other States, under the name of the ‘United States of America,’ is hereby dissolved.” Other Southern states soon followed suit, and by the spring of 1861 the once impossible nightmare of civil war seemed increasingly likely.

But Thoreau did not recover. The influenza had apparently exacerbated a dormant case of tuberculosis, a scourge of New England that had already carried off one of his sisters. For the next year or so he tried intermittently to venture into the woods, to visit the placid blue-green waters of Walden, to sit outside and absorb the sunlight. More often than not weakness assailed him, and he was forced to turn back. His cough grew worse. Alcott visited his friend and observed that being housebound was “a serious thing to one who has been less a housekeeper than any man in town, has lived out of doors for the best part of his life, has harvested more wind and storm, sun and sky, and has more weather in him than any.”

Just before the Battle of Bull Run produced the first Union defeat in the summer of 1861, Thoreau embarked on a long train trip to Milwaukee, hoping the climate would improve his health. It did not. At some point he realized he would never recover, that it was time for a strict closing of accounts. He embarked on the bittersweet process of putting his manuscripts in order, extracting from his sprawling notebooks a few essays for the Atlantic. By the following spring he was a wraith. In March 1862 he wrote an admirer of Walden, “I suppose that I have not many months to live; but, of course, I know nothing about it. I may add that I am enjoying existence as much as ever, and regret nothing.” A friend, Sam Staples, visited Thoreau a few days later and reported to Emerson that he had never seen “a man dying with so much pleasure and peace.”

The spring of 1862 was refulgent with new growth and renewal. It was also shadowed by the resumption of fighting between Union and Confederate forces after winter. That March Thoreau could barely see or speak. He could no longer hold one of his family’s pencils. His cumbersome breathing filled the second floor of his mother’s house, where he had been moved. “Elizabeth Hoar is arranging his papers,” Abba Alcott wrote her brother, Samuel May, on March 24, 1862, “— Miss [Sophia] Thoreau copying for him—he is too weak to do any of the mechanical part of himself.”

At some point his aunt visited his sickroom to ask, “Have you made your peace with God?”—to which Thoreau replied, “We never quarreled.” When another acquaintance asked, “Are you ready for the next world?” his response was sardonic and mirthful: “One world at a time.”

He died on May 6, 1862. News spread fast throughout Concord, prompting Sarah Alden Ripley to lament, “This fine morning is sad for those of us who sympathize with the friends of Henry Thoreau, the philosopher and the woodman.” Bronson Alcott visited during his final day, describing Thoreau as “lying patiently & cheerfully on the bed he would never leave again. He was very weak but suffered nothing & talked in his old pleasant way saying ‘it took Nature a long time to do her work but he was most out of the world.’” Against Thoreau’s wishes, Emerson arranged a funeral service at the First Church, his sorrow “so great he wanted all the world to mourn with him.” Speaking at the memorial, Emerson said of his friend’s unfinished natural history manuscript, “The scale on which his studies proceeded was so large as to require longevity, and we were the less prepared for his sudden disappearance. . . . It seems an injury that he should leave in the midst his broken task, which none else can finish,—a kind of indignity to so noble a soul, that it should depart out of Nature before yet he has been really shown to his peers for what he is.”

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From THE BOOK THAT CHANGED AMERICA: How Darwin’s Theory of Evolution Ignited a Nation by Randall Fuller, published on January 24, 2017 by Viking, an imprint of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright © 2017 by Randall Fuller.